Cooperative Hand Therapy via a Soft, Wearable, and Unilateral Telerobotic System

Abstract

Functional rehabilitation of the hand is a complex and difficult process involving a large number of degrees of freedom (DOFs). Soft wearable hand-rehabilitation robots have assisted hand movements with a compact structural design, but effective rehabilitation requires an intuitive control scheme that can manage many DOFs and incorporate interaction with an occupational therapist, which has yet to be developed for this type of device. Thus, we present a soft wearable unilateral telerobotic system that enables various grasping tasks and cooperative interaction between the patient and therapist. The presented system consists of a sensor glove that measures the hand postures of the occupational therapist and a soft robotic glove that assists 4-DOF movements of the patient's hand, including adjustments of the interjoint coordination of the finger and 2-DOF movements of the thumb (flexion/extension and opposition/reposition). The soft robotic glove effectuates hand movements based on the measurements from the sensor glove. A telerobotic impedance-control scheme provides intuitive guidance of various hand postures, along with a fingertip-force vector. The feasible workspace and control performance of the system were evaluated on a healthy recruit and a poststroke patient. The presented system allowed the therapist to increase the patient's thumb workspace by 400% in palmar-dorsal direction and to control the fingertip-force direction at -30°∼10° range by enabling control of interjoint coordination of the proximal-interphalangeal and metacarpophalangeal joints. These features facilitate patients to perform various postures for stable object grasping. The presented rehabilitation system is suitable for noncontact telehealthcare that facilitates patient–therapist interactions.